Wisconsin Gov. Scott Walker is not content to give fellow GOP presidential candidate Donald Trump a win in the battle over who can pledge more to keep us safe from scary immigrants.

Trump thinks promising a "great" wall along the 2,000-mile U.S.-Mexico border is enough?

Walker, floundering in the polls, trumped Trump this week when he said he would consider building a wall along the entire 5,525-mile U.S.-Canada border.

More coverageOpinion and analysis about the 2016 presidential campaign

On NBC News' "Meet the Press," Walker said, "Some people have asked us about that in New Hampshire. They raised some very legitimate concerns, including some law enforcement folks that brought that up to me at one of our town hall meetings about a week and a half ago. So that's a legitimate issue for us to look at."

Can another candidate top Walker?

Gov. Chris Christie of New Jersey tried by suggesting tracking immigrants like FedEx packages, an idea that conjures up grim images. And no one yet has suggested a wall 70,000 feet high around international airports, which is what we might need to stop the many visitors who came in on planes and stayed illegally.

advertisement | advertise on newsday

Nor have any pointed out the staggering vulnerability of our Eastern and Western borders, the great Atlantic and Pacific oceans.

Fighting for 1,500-mile sea walls would have political upside, but suggesting them also might be risky: It could make Republican politicians look as if they believe in and want to combat the effects of global warming.